Varian Solid-State NMR - Figure 33. Pulse Sequence for Measuring H T

6.1 XPOLAR—Cross-Polarization, UNITY
01-999162-00 C0402 VNMR 6.1C User Guide: Solid-State NMR 84
obtained just as with any other text file. The graphical display of the data can be viewed on
screen by using the command exp1 or plotted with the command pexp1.
Measurement of the
1
H T
1
through Cross-Polarization
Proton T
1
can be measured using the XPOLAR pulse sequence by performing a standard
inversion-recovery experiment on the protons followed by cross-polarization of the
remaining
1
H magnetization to the carbons. Figure 33 is a diagram of the pulse sequence.
The xpolar macro sets up parameters for the XPOLAR pulse sequence.
Parameters
xpol is set to 'n' for direct polarization or set to 'y' for cross-polarization.
pw is the observe pulse for direct polarization or the proton 90
° pulse for cross-polarization.
pw is in microseconds.
p1 is the initial observe pulse (direct polarization), usually set to a 180°° inversion pulse,
or the initial proton pulse, usually set to a 180
° pulse (cross polarization). p1 is in
microseconds.
p2 is the cross-polarization contact time, in microseconds.
p3 is a pulse, in microseconds, for an X-nucleus only spin-lock following p2.
dm should be set to 'nny'. The decoupler has a maximum duty cycle of 20%.
d2 is delay between p1 and pw (for inversion-recovery) if pdp='n'. If pdp='y', d2 is
a delay for interrupted decoupling for protonated carbon suppression. d2 is in seconds.
srate is the sample spinning rate, in Hz.
toss set to 'y' invokes timed spin-echoes to suppress spinning side bands.
level1 controls decoupler power during cross-polarization.
level1f controls fine decoupler power during cross-polarization.
level2 controls decoupler power during acquisition.
level2f controls fine decoupler power during acquisition time.
level1 and level2 control decoupler power and should be used for Hartmann-Hahn
matching. The decoupler is set with the config display and can be either class C, with a
Figure 33. Pulse Sequence for Measuring
l
H T
1
13
C
xpol='y'
1
H
p2
d1
p1
d2
pw
level1
level2